The present invention relates to a positioning device suitable for use in IC test equipment for testing, for instance, surface-mounting-type IC's and an IC conveyor for bringing an IC to be tested from a predetermined position to a test socket disposed at a testing position and for bringing the tested IC from the test socket to another position.
IC's can be split into DIP-type and surface-mounting-type ones according to the type of mounting to the printed circuit board.
Because of the structure of its terminals the surface-mounting-type IC cannot be mounted astride a guide rail for conveyance to the position of the test socket in the IC tester. For this reason, the surface-mounting-type IC is picked up by an air chuck, which is moved to bring the IC to the position of the test socket.
The IC testing device includes an auto-handler for automatically conveying an IC to the position of the test socket, removing therefrom the tested IC and conveying it to a storage after assorting it into a non-defective or defective, and a test head for receiving on the test socket the IC conveyed thereto by the auto-handler and electrically connecting each terminal of the IC to the tester.
FIG. 1 shows an example of such an IC testing device. Reference numeral 10 indicates an auto-handler, 20 a test head and 30 a tester. The auto-handler 10 includes: a constant temperature bath for heating or cooling an IC to be tested to a desired temperature; a storage for storing the IC's to be tested; a storage for storing tested IC's assorted into non-defectives and defectives; a conveyor for conveying the IC to be tested from the storage to the constant temperature bath; a conveyor for conveying the IC from the constant temperature bath to a position just above the test head 20; a conveyor for loading the IC to be tested onto a test socket disposed at the upper portion of the test head 20 and for unloading the tested IC from the socket; and a conveyor for conveying the unloaded IC to a non-defective or defective storage.
The test head 20 has the test socket at its upper portion and the test socket is connected via a cable 21 to a tester 30. The auto-handler 10 is a mechanical unit, whereas the test head 20 is an electric circuit unit. The auto-handler 10 and the test head 20 are produced separtely and combined by a common frame 11. The positioning accuracy necessary for the IC conveyor of the auto-handler 10 to load the IC onto the test socket of the test head 20 is on the order of microns.
As shown in FIG. 2, the test head 20 has a performance board 22 fixedly mounted thereon, the performance board 22 having at its center a test socket 23 detachably mounted thereon. Above the test socket 23 there is provided an IC conveyor 13 of the auto-handler 10 in a manner to be movable laterally. That is, a rail 12 is installed in the X-axis direction, on which the IC conveyor 12 is movably mounted.
Under the IC conveyor 13 there is provided an air chuck 13A, on which there is provided a lifting gear 13B. An IC to be tested 40, brought by a first conveyor 16 to the loading position, is picked up by the air chuck 13A, by which it is brought to the position above the test socket 23 and then loaded thereon. Upon completion of the test, the lifting gear 13B is actuated, by which the IC is unloaded from the test socket 23 and then taken over to a second conveyor 17 disposed at an unloading position.
The first and second conveyors 16 and 17 respectively comprise straight rails 16A, 17A and carriages 16B, 17B which are guided by the rails 16A, 17A. The first conveyor 16 conveys the IC to be tested 40 from the constant temperature bath to the position just above the test head 20. The second conveyor 17 brings the tested IC 40 back to the storage.
When the IC to be tested 40 is brought thereto by the first conveyor 16, the IC conveyor 13 lowers the air chuck 13A, causes it to pick up the IC 40, raises air chuck 13A, moves in the X-axis direction, stops at a predetermined position above the test socket 23 and then lowers the air chuck 13A to load the IC 40 onto the socket 23. At this time, terminals of the IC 40 must be connected to predetermined contacts of the test socket 23. It is therefore necessary that the IC 40 brought by the IC conveyor 13 to the predetermined position accurately bear a predetermined positional relationship to the test socket 23.
A positional error between the test socket 23 and the IC 40 brought to the predetermined position above the test socket 23 is a combination of translational and angular displacements as depicted in FIGS. 3 and 4. That is, the positional error can be divided into a displacement of the IC 40 in each of the X-axis and Y-axis directions in parallel thereto as shown in FIG. 3 and an angular displacement relative to each of the X-axis and Y-axis directions, i.e. a rotational displacement in the X-Y plane as shown in FIG. 4.
The positional error in the X-axis direction can be avoided by adjusting the stop position of the conveyor 13, whereas the positional error in the Y-axis direction can similarly be avoided by adjusting the stop position of the first conveyor. In addition, the stop positions of the conveyors 13 and 16, once set, can be reproduced with high accuracy any number of times.
It is necessary, however, to adjust the stop positions in the X-axis and Y-axis directions several times alternately with each other every time the test socket 23 is changed for each kind of an IC to be tested. Besides, the positional error resulting from the rotatory motion such as shown in FIG. 4 cannot be eliminated even by the adjustment of the stop positions of the conveyors 13 and 16. The position error of this kind can be avoided only by adjusting the mounting position of the test head 20 on which the test socket 23 is mounted through the performance board 22, but this is difficult, because the weight of the test head 20 is very large.